X-rays and other forms of radiation have traditionally been used in diagnostic medicine with photographic film. This has also been utilized in screening female patients for breast cancer in mammography. While photographic film can provide adequate resolution, it has a number of drawbacks. It is expensive. Its costs being tied to the market price of silver. It requires chemical development, which, even with "high speed" development equipment, is time consuming. The chemical development process generates waste chemicals which must be disposed of properly, or generate environmental problems.
While charged coupled device (CCD's) detectors can be effectively employed in filmless X-ray image detection such detectors are costly, limited in size, and usually require a phosphor coated plate, which is illuminated by the transmitted X-rays and which is captured by the CCD.
X-ray images can also be obtained in other filmless electronic processes, but such processes often present different problems. For example, one of the most important requirements in filmless, digital image formation, in an area such as mammography is to obtain spatial resolution of an X-ray detector on the order of from about 30 to about 50 microns. This severe requirement is difficult to meet by the presently available position sensitive electronic detectors which are potential candidates for fast filmless digital mammography. The practical resolutions obtainable are often limited by the physical phenomena involved in the process of X-ray detection, such as parallax effect due to photon range, conversion point definition due to photoelectron range, and diffusion caused by electron ionization.
The present invention overcomes the deficiencies of the prior art.